OFDM and OFDMA wireless communication systems under IEEE 802.16 use a network of base stations to communicate with wireless devices (i.e., mobile stations) registered for services in the systems based on the orthogonality of frequencies of multiple subcarriers and can be implemented to achieve a number of technical advantages for wideband wireless communications, such as resistance to multipath fading and interference. Each base station (BS) emits and receives radio frequency (RF) signals that convey data to and from the mobile stations (MS).
In an effort to conserve power at the MS, the IEEE 802.16 standard defines power savings class (PSC) modes, where the MS may power down one or more components during sleep windows. The MS periodically wakes up to monitor for activity during listening windows to decide whether the PSC mode should be exited. The MS may enter PSC modes separately for different connections with the same base station. Unfortunately, however, the MS must power up components during the listening window for each connection. Because the listening window for one connection may overlap with the sleep window for another connection, power savings is not optimal.
Accordingly, what is needed is an improved technique for conserving power in an MS.